Which one is better in your opinion and why? Also, I plan to get one used, will there be a problem with any online functions? I am not sure how Nintendo's network works.  

nintendo network settings only allows you to connect to up to 3 and there is some features too...

3DS XL is probrably the best one to go cause the normal 3DS is small.  

Hmm... I'm going to be completely honest and say that I have not played the 3DS XL. I only own the normal 3DS. I think I heard there are some advantages to the normal 3DS with the joystick playing Smash Bros. in comparison to the XL. When I'm playing a game like Pokemon Y during 3 vs 3 there is noticeable lag which I assume would be much less on the XL. The XL is probably more enjoyable to play with a bigger screen too. Sorry if I'm not being that helpful. I would have to say that the XL would probably be the better choice overall.  

3DS XL  

@ Tyler - when playing pokemon or/as you could still get lag on the XL but only playing on 3 vs 3 on 2 vs 2 it isnt that laggy or anything  

Wait for NEW 3DS.  

Posted by Tyler

Hmm... I'm going to be completely honest and say that I have not played the 3DS XL. I only own the normal 3DS. I think I heard there are some advantages to the normal 3DS with the joystick playing Smash Bros. in comparison to the XL. When I'm playing a game like Pokemon Y during 3 vs 3 there is noticeable lag which I assume would be much less on the XL. The XL is probably more enjoyable to play with a bigger screen too. Sorry if I'm not being that helpful. I would have to say that the XL would probably be the better choice overall.

Any idea as to whether or not getting a pre-owned system would effect anything? Would I be using someone else's network ID or do they change? I have no idea besides little tidbits from yahoo answers.  

dont get a pre-owned cause there might be chances that the nintendo itself is banned globally for using pirated games.  

Lmao that is true. Too bad though because I only have $70  

I have a 3DS and I wish I had waited for the 3DS XL.  

Posted by Kuuga

Wait for NEW 3DS.

I thought about this but I didn't really see a point in it. I couldn't see what differences would make me want to wait.  

I have used both devices and I can say the XL is much more enjoyable due to the larger screen.  

I love my 3DS simply because it can fit in my pocket easier.  

XL is my recommendation.
Alternatively, the New 3DS XL is a good choice.  

I have all the 3DS XL Zelda Edition !